The present invention is related to assisting the operation of a patient""s heart. More specifically, the present invention is related to assisting the right ventricle (RV) function of a patient.
When pharmacological agents are unable to improve RV function, surgeons must rely on mechanical means to restore blood flow to the pulmonary circulation and left ventricle. Current options for mechanical assist include: centrifugal pumps; positive displacement pumps; and right-sided balloon counterpulsation. The drawback common to all these mechanisms is that they require invasive, time-consuming procedures to secure requisite cannulae and/or anastomoses to the pulmonary artery (unlike IABP assist of the left ventricle which can be positioned and retracted through a femoral artery cutdown).
The present invention was developed to provide a quick and simple means to assist the failing right ventricle. The inspiration for the present invention was the technique of cardiopulmonary resuscitation, in which the chest wall is physically compressed to cause ejection of blood from an arrested heart. The idea was to use expansion/deflation of a balloon within the chest cavity to achieve a similar result. It was believed intuitively that this approach would be more successful for RV assistance because the pulmonary circulation is a low resistance circuit that operates at a pressure 25% of that for the systemic circulation.
The present invention, unlike those currently available, allows minimally-invasive RV assist through a small subxiphoid incision. The expanding and collapsing mechanism can be rapidly deployed and is positioned in the anterior mediastinum. Expanding and collapsing mechanism removal can be effected by simply retracting the balloon from the pericardial space in a manner similar to removing a chest tube.
A discussion of RV assist devices and the treatment of RV failure appears in a review article by R. Higgins and J. Elefteriades titled xe2x80x9cRight Ventricular Assist Devices and the Surgical Treatment of Right Ventricular Failurexe2x80x9d, Cardiology Clinics, Volume 10, Number 1, February 1992, incorporated by reference herein.
Some characteristics which separate the present invention from other compression devices or RV assist devices currently on the market are its:
low cost
mechanical simplicity
ease of use (esp. insertion and removal)
does not encircle the heart or directly compress the LV and
designed to assist the RV with LV assistance as a secondary consideration.
The present invention pertains to an apparatus for assisting a patient""s heart function. The apparatus comprises a mechanism for expanding and collapsing a right ventricle free wall of a heart of a patient. The apparatus also comprises a mechanism for powering the expanding and collapsing mechanism. The powering mechanism is in communication with the expanding and collapsing mechanism.
The present invention pertains to a method for assisting function of a patient""s heart. The method comprises the steps of expanding a balloon placed between a right ventricle free wall and a septum of a patient such that right ventricular compression is achieved during cardiac systole. Then there is the step of collapsing the balloon during cardiac diastole.